accepting payments with unknown dollar amount

Merged

I use to have simple store which allowed the customer to type in the amount they wished to pay me. I have a service industry business and don't a item to buy on a website. I need a way for them to send me a payment that they enter the amount they wish to pay. Simplestore with Intuit merchant account use to allow me to do this. Is there any other options? Paypal only allows particular items to be sold.